This adds checks for allocations and type values, and provides a compile
time error for type declarations, is-checks, and as-casts.
Change-Id: I3bfed41b0dd45abeb02158f0537102c779511998
Reviewed-on: https://dart-review.googlesource.com/36383
Commit-Queue: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Peter von der Ahé <ahe@google.com>